Autophagy activated by tuberin/mTOR/p70S6K suppression is a protective mechanism against local anaesthetics neurotoxicity

Abstract

The local anaesthetics (LAs) are widely used for peripheral nerve blocks, epidural anaesthesia, spinal anaesthesia and pain management. However, exposure to LAs for long duration or at high dosage can provoke potential neuronal damages. Autophagy is an intracellular bulk degradation process for proteins and organelles. However, both the effects of LAs on autophagy in neuronal cells and the effects of autophagy on LAs neurotoxicity are not clear. To answer these questions, both lipid LAs (procaine and tetracaine) and amide LAs (bupivacaine, lidocaine and ropivacaine) were administrated to human neuroblastoma SH‐SY5Y cells. Neurotoxicity was evaluated by MTT assay, morphological alterations and median death dosage. Autophagic flux was estimated by autolysosome formation (dual fluorescence LC3 assay), LC3‐II generation and p62 protein degradation (immunoblotting). Signalling alterations were examined by immunoblotting analysis. Inhibition of autophagy was achieved by transfection with beclin‐1 siRNA. We observed that LAs decreased cell viability in a dose‐dependent manner. The neurotoxicity of LAs was tetracaine > bupivacaine > ropivacaine > procaine > lidocaine. LAs increased autophagic flux, as reflected by increases in autolysosome formation and LC3‐II generation, and decrease in p62 levels. Moreover, LAs inhibited tuberin/mTOR/p70S6K signalling, a negative regulator of autophagy activation. Most importantly, autophagy inhibition by beclin‐1 knockdown exacerbated the LAs‐provoked cell damage. Our data suggest that autophagic flux was up‐regulated by LAs through inhibition of tuberin/mTOR/p70S6K signalling, and autophagy activation served as a protective mechanism against LAs neurotoxicity. Therefore, autophagy manipulation could be an alternative therapeutic intervention to prevent LAs‐induced neuronal damage.

<p>Tetramethylpyrazine attenuated bupivacaine-induced neurotoxicity in SH-SY5Y cells through regulating apoptosis, autophagy and oxidative damage</p>

“…In addition, a previous study also indicated that BUP could mediate the upregulation of LC3II and the downregulation of P62. 21 Differently, our study showed that BUP (500 μM) could not induce autophagy in SH-SY 5Y cells. The difference between our result and previous study might reflect differences in the dose of BUP exposure (500 μM vs 900 μM).…”

“…Autophagy also plays important roles in neuro-cell survival and death, and is receiving increasing focus in neurotoxicity research. 21 A previous study indicated that small molecules demonstrate a neuroprotective effect by enhancing autophagy and inhibiting apoptosis, such as flubendazole, flupirtine and aromatic carbamates. [22][23][24] In addition, dexmedetomidine protects neurons from the toxicity of the anesthetic sevoflurane by enhancing autophagy and inhibiting apoptosis.…”

“…The difference between our result and previous study might reflect differences in the dose of BUP exposure (500 μM vs 900 μM). 21 In order to confirm whether TET-induced autophagy is pro-proliferative or proapoptotic, we used autophagy inhibitor 3MA to suppress SH-SY5Y cell autophagy. Our results indicated that 3MA significantly inhibited TET-induced autophagy.…”

Ameliorating Ribosylation-induced Aβ Pathology by Berberine via Inhibiting mTOR/p70S6K Signaling

“…During the formation of autophagosome, microtubule-associated proteins light chain 3A (LC3A) is actived by autophagy related protein 7 (ATG7), transferred to ATG3, then conjugated with phosphatidyl ethanolamine to form LC3B. SQSTM1/p62 is a key factor in the formation of autophagosome and is selectively degraded in autolysosome system (43). Our recent study has found that autophagy disorder enhanced the production of Aβ by enhancing the activity of the γ-secretase complex.…”

Protective effects of extracellular polymeric substances from Aphanizomenon�flos‑aquae on neurotoxicity induced by local anesthetics

“…One pharmacological strategy against the neurotoxicity of local anesthetics is the use of drugs to induce autophagy to treat the associated diseases (2,3). Studies have shown that certain drugs can directly or indirectly activate autophagy to prevent cell death (4,5).…”